The isolation of small, approximately 100 basepairs, restriction fragments of T7 DNA carrying promoters for the phage-specified T7 RNA Polymerase (single polypeptide chain, MW 100,000) have provided a simple in vitro system to study the mechanism of transcription. The precise molecular interactions of the polymerase with these promoters will be examined by spectroscopic, chemical modification, radiolabeling and kinetic methods. The molecular properties of T7 RNA polymerase are being determined as well as the sequence of the polymerase gene and hence the amino acid sequence. Multinuclear NMR (1H, 31P and 19F) methods are being used to probe the structure of the complexes of gene 5 protein of bacteriophage fd and gene 32 protein of bacteriophage T4 with oligedeoxynucleotides of defined sequence. The role of phosphorylation-dephosphorylation in the structure and function of non-histone chromosomal proteins is under investigation.